In the conventional mobile terminal management system, standardization is conducted by the IETF (Internet Engineering Task Force) Mobile-IP (Internet Protocol) working group, the standardizing organization for data sent over the Internet. Further, standardization of the mobile network management format where not only the terminal but rather the network in its entirety is to move is being planned by the IETF NEMO (Network Mobility) working group. JP-A-H8-237717 describes a conventional mobile network management technology.
Using figures, an explanation of this network management is made below.
FIG. 17 is a diagram showing an arrangement of a conventional mobile network management system. Home network 1001 is arranged with a home gateway 1003 connected to the Internet and a position management server 1002, wherein a mobile network 1004 is connected to the home network 1001 which is the home of the mobile network 1004. The mobile network 1004 is arranged with a mobile router 1005 holding an interface to an external network and an interface to an internal network, and a host node 1006. External network 1007 comprises an external access router 1008. Furthermore, there exists a communication node 1010 for communication with the mobile network 1004 by way of the Internet 1009.
In the document “Network Mobility (NEMO) Basic Support Protocol” (IETF NEMO WG, draft-ietf-nemo-basic-support-0.2.txt, December 2003), mobile router 1005 belongs to home network 1001 and has the home network prefix “Home Prefix” which is given to all the addresses of the home network 1001, and a network address “Home Prefix::10” generated from its own hardware address “10”. This address is the sole address of mobile router 1005 over the Internet. Alternatively, if Prefix A is allocated as the network prefix within mobile network 1004, host node 1006 has a network address PrefixA::20, taken from its own hardware address “20”.
In case the mobile router 1005 moves into a connection with a certain external network 1007, external access router 1008 of external network 1007 allocates an external network prefix “Foreign Prefix” to mobile router 1005. Mobile router 1005 establishes a tentative address for external network 1007, “Foreign Prefix::10”, generated from the external network prefix “Foreign Prefix” and its own hardware address “10”.
Mobile router 1005 gives its own tentative address “ForeignPrefix::10” to position management server 1002 of home network 1001, in order to transfer a packet. Position management server 1001 stores the received tentative address “ForeignPrefix::10” of mobile router 1004 and home address “HomePrefix::10” as a related pair.
Then, in the case where a data packet is to be sent from communication node 1010 existing on another network to the mobile router 1005 in question, communication node 1010 is not aware of a movement of the relevant router 1005, so the data packet is first sent to home network 1001 whether or not mobile router 1005 is connected to home network 1001.
In case the data packet destined for mobile router 1005 is sent from communication node 1010 to home network 1001, position management server 1002 in the relevant home network 1001 catches a packet having the mobile router 1005 home address “HomePrefix::10” which has been stored in the server memory, and transfers the data packet to the external network 1007 because the external address corresponding to the home address is “ForeignPrefix::10”.
In the case of sending the data packet from communication node 1010 to host node 1006, transmission is made to the address “PrefixA::20” of host node 1006. The packet destined for that address is first sent to home network 1001 and then sent to mobile router 1005, which is the next hop router according to the routing table held by the home gateway. However, position management server 1002 catches the packet destined for the home address “HomePrefix::10” and sent by mobile router 1005, and transfers the data packet to the external network 1007 because the external address corresponding to the home address is “ForeignPrefix::10”.
In this manner, in the conventional data communication, mobile router 1004 has two addresses, i.e. address in the home network 1000 and address in an external network 1007. Position management server 1001 in home network 1000 manages the positional information of the relevant mobile router 1004, and transfers a data packet. In this way, packet routing is realized which can adapt to the change in address identification due to movement of mobile router 1004.
Conventionally, in the case where a router is newly connected to the network, an IP address is automatically allocated from a DHCP (Dynamic Host Configuration Protocol) server. However, the address allocated by the DHCP server is recognized only within the sub-networks to which the DHCP belongs. It cannot be adapted to the case where the mobile router moves into a connection with another external network. For this reason, the “home address” of the mobile router must be set manually by the user, or else a connection must be made to the home network at the initial startup without exception, to be allocated an temporary address from the position management server.
However, where the mobile management server is set up by a ordinary service provider instead of a user having a mobile router, there is no way to establish a home address ahead of time because of the manufacturers of mobile routers and host nodes are different. Thus, there is a problem that the user must have a home address for mobile router and a network prefix for mobile network allocated from the contracted provider, and manually make settings.